(1) Field of the Invention
This invention relates to a controller for a vehicle engine (internal combustion engine) equipped with a power-controlling throttle valve in an intake passage thereof. In particular, the present invention is concerned with a device for controlling a vehicle engine by controlling a throttle valve provided in an intake passage of the engine in accordance with the drive-by-wire method in such a way that instead of mechanically connecting the throttle valve with a mancontrolled member arranged in a vehicle operating room such as the interior of a vehicle, such as an accelerator pedal, the throttle valve is rendered controllable by an actuator such as electric motor, thereby outputting to the actuator a control signal based on the degree of operation of the man-controlled operation member such as the accelerator pedal and permitting the opening/closing control of the throttle valve.
(2) Description of the Prior Art:
A throttle valve interposed in an intake passage of an engine has heretofore been driven by a wire connected to an accelerator pedal.
Such a conventional throttle valve controller of the mechanical link system however involves potential inconvenience that the responsibility may be deteriorated due to slacking or play of the wire and the feeling of the accelerator pedal may be impaired due to twisting, corrosion or the like of the wire.
In an attempt to overcome such potential inconvenience, it has been proposed to drive a throttle valve in accordance with the throttle-by-wire method while using information on the position of an associated accelerator pedal as an input signal as disclosed in U.S. Pat. No. 4,519,360 of May 28, 1985 by way of example. Such conventional controllers cannot however improve the drivability fully, because the opening rate of the throttle valve is in direct 1:1 proportion with the stroke of the accelerator pedal.